The effects of ionic liquids as additives on the dispensability and lubricating properties of graphene lubricating oils were investigated.The dispersion stability of ionic liquid/graphene lubricating oil was investigated by changing the ionic liquid mass fraction,ultrasonic power and time.The tribological behaviors of ionic liquid/graphene lubricating oil under different conditions were investigated by using Rtec multi-functional friction and wear test machine and with Si3N4/steel as friction pair,and the worn surface was analyzed by scanning electron microscopy and ultra depth of field microscopy to explore the lubrication mechanism of ionic liquids as additives.The results show that the dispersibility and improved when the mass fraction of ionic liquid is 0.002 5%,the ultrasonic time is 60 min and ultrasonic power is 600 W.After the addition of ionic liquid/graphene,the lubrication performance of the lubricating oil is improved.The friction coefficient of lubricating oil is decreased with the increase of the mass fraction of the ionic liquid and the increase of the ultrasonic power,and increased with the increase of the ultrasonic time.It is found that due to the longchain structure of the ionic liquid cation and its high viscosity,the lubricating film composed of ionic liquid is thick and easy to be adsorbed on the surface of friction pair.And due to the synergistic effect of ionic liquid and graphene,the mixed lubricating film is formed,which avoids the direct contact between the friction pairs and improves the tribological performance.